Automatic drain valve



July 26, 1938. B, s, A RMAN 2,125,145

' AUTOMATIC DRAIN VALVE Filed Aug. 29, 1956 INVENTOR BURTON AMMANATTORNEY Patented July 26, 1938 UNITED STATES PATENT OFFICE AUTOMATICDRAIN VALVE Application August 29, 1936, Serial No. 98,518

13 1 Claims.

This invention relates to an automatic drain valve device for use on thereservoir or receiver of a fluid pressure system and which operates todrain liquid which may accumulate in this reservoir.

In the operation of fluid pressure systems, such as a fluid pressurebrake equipment, air from the atmosphere is compressed and is stored ina reservoir or receiver from which fluid is withdrawn during operationof the equipment. As a result of the supply of fluid under pressure toand the release of fluid under pressure from the reservoir water may bedeposited in the reservoir, and unless it is drained off, it accumulatesin thereservoir and reduces the volume of the reservoir, while it mayfreeze and'cause injury to the reservoir.

It is an object of this invention to provide valve means which operatesautomatically to drain liquid which accumulates in the reservoir of afluid pressure system.

A further object of the invention is to provide valve means responsiveto the release of fluid from a reservoir for draining off liquid presentin the reservoir. I

Another object of the invention is to provide valve means which operatesto drainoff substantially all of the liquid in the reservoir each timethe valve means is operated.

A further object of the invention is to provide a valve device of thetype described, and having means responsive to the level of the liquidin the reservoir for cutting off the flow of fluid from the reservoirthrough the valve device when the level of the liquid therein has beenreduced to a predetermined level.

Another object of the invention is to provide a valve device of the typedescribed and which has its operating elements positioned above thelevel of the liquid in the reservoir so that the valve device will notbe injured if the liquid in the reservoir freezes.

A further object of the invention is to provide an improved automaticdrain valve device.

Other objects of the invention and features of novelty will be apparentfrom the following de-- scription taken in connection with theaccompanying drawing, the single figure of which is a sectional viewshowing a reservoir equipped with a drain valve device embodying myinvention.

Referring to the drawing, the automatic drain valve device provided bymy invention is shown in connection with a reservoir I, which issupplied with fluid under pressure through a pipe 2 by a compressor, notshown. The reservoir I may be of any suitable construction, and may bepart of a fluid pressure system, such as a fluid pressure brakeequipment.

The reservoir I has an opening therein adjacent the uppermost portionthereof, and a body 4 is secured in this opening. The body 4 has acontrol chamber 6 formed therein to which is connected a service pipe 8through which fluid is withdrawn from the reservoir I.

A tubular sleeve I0 is secured in the body 4 and communicates with thecontrol chamber 6 and with the upper portion of the reservoir I, whilethe body 4 has secured thereto a tube I2 of smaller diameter than thesleeve l I]. The tube I2 extends through the sleeve II] and communicateswith the lower portion of the reservoir I, as will hereinafter morefully appear. The sleeve I0 has a seat rib I4 formed thereon within thechamber 6, while a valve disc I6 is loosely mounted on the tube I2 andis yieldingly held in engagement with the seat rib I4 by a spring I8.

The body 4 has a bore therein in which is mounted a movable abutment inthe form of a piston 20 having at one side-thereof a chamber 22, whichis constantly connected by way of a passage 24 with the control chamber6, while the piston 20 has at the other side thereof an operatingchamber 26, which is connected through passages 28 to the passage withinthe tube I2.

The piston 20 has a groove in the periphery thereof in which is mounteda packing ring 30, which is yieldingly pressed against the wall of thebore in which the piston 20 is mounted by the inherent resiliency of thematerial of which it is constructed so as to develop considerablefrictional resistance to movement of the piston 20 in the bore in thebody 4.

The piston 20 has formed integral therewith a valve 32, which is adaptedto seat upon a seat formed on the body 4 surrounding a passage in whichis secured a tube 34 of smaller diameter than the tube I2, and mountedwithin the tube I2.

The tube 34 is of such length as to extend through an opening in thewall of a cup 36, which is secured in an opening in the reservoir Idiametrically opposite the'opening in which the body 4 is mounted. Thecup 36 is substantially at the lowest portion of the reservoir I so thatliquid which accumulates in the reservoir I will flow to this cup bygravity.

The opening in the wall of the cup 36 through which the tube 34 extendsis sealed by means The tube I2, which is carried by the body 4,

is of such length as to extend into the cup 36 secured at the lowerportion of the reservoir I, and has secured on the lower end thereof asubstantially circular member 42 having passages 44 therein, whichcommunicate with the passage through the tube I2, and with portson theupper face of the member 42. The upper face of the member 42 issubstantially flat and is adapted to be engaged by a float 46, which maybe formed of any suitable material, such as cork. The float 46 isloosely mountedon the tube I2, and on a decrease in the level of theliquid in the cup 36, the float is moved by gravity into engagement withthe upper face of the member 42 so as to substantially out ofl the flowof fluid from the reservoir I to the: passages 44 in the member 42. I 1;

' The member 42 hasan opening therein throu'gh which extends the tube.The tube 34 tightly fits in this opening so as to prevent the flow offluid from the reservoir I to the passage'in the tube I2 through theopening in the member 42 through which the tube 34 extends. I i

In operation, on the initial supply of fluid under pressure to thereservoir I, fluid will flow therefrom through the passage in thetubular sleeve I6 and past the valve disc I6 tothe control chamber 6,and therefrom by way of the passage 24 to the chamber 2 2 to increasethe pressure of the fluidin, these chambers to the pressure of the fluidin the reservoir I..

On the initial supply of fluid under pressure to the reservoir Isubstantially no liquid will be present in the cup 36, and the float 46will be in engagement withthe upper face of themember 42 so as toprevent the flow 'of fluid'from the reservoir to the passages 44. v

Fluid supplied tothe chamber .22 wil1 leak past thegpiston 26 andtheipiston packing ring 36 and increase the pressure of the fluid in theoperating chamber 26 substantially to the pressure of the'fluid in thereservoir I. ,7

i As the area within the seat engaged by'the valve 32 is not subjectto-the fluid under pressure in the operating chamber 26, the efiectivearea of the face of the piston 26 subject to the fluid under pressure inthe operating chamber 26 is somewhat less than the area of the face ofthe piston 26 subject to the pressure of the fluid in the chamber 22 atthe opposite face of the piston, so that even if the pressure of thefluid in the chamber 26 is increased to the. pressureof the fluid in thereservoir I, the piston 26 ,will be held in a position in which thevalve32. carried thereby engages its seat to cut off the release offluid from the chamber 26. to the atmosphere through the tube 34.

I. In addition, the piston 26 will beheld in the position in which thevalve 32 engages its seat by the piston packing ring 36, which opposesmovement of the piston 20 in the bore in which it is mounted. 7

On the withdrawal of fluid under pressure from the reservoir throughtheservice pipe 8 there is a rapid reduction in the pressure of thefluid in the control chamber 6, and a corresponding reduction in thepressure of the fluid in the chamber 22 at'the face of the piston 26. Onthis reduction in the pressure of the'fluid in the control chamber 6,the valve disc I6 is moved upwardly against the opposing force of thespring I8 by the higher pressure of the fluid in the reservoir I so asto permit fluid under pressure to flow from the reservoir I to thecontrol chamber 6 and therefrom to the service pipe 8. There will,however, be a small difference between the pressure of the fluid in thecontrol chamber 6 and the pressure of the fluid in the reservoir I dueto the operation of the valve disc I6.

If at this time the level of the liquid in the cup 36 is not high enoughto lift the float 46 away from the face of the member 42, the operatingchamber 26 at the face of the piston 26 will not be open to thereservoir through the pipe I2. However, fluid is present in theoperating chamber 26 at'the pressure of the fluid in the reservoir atthis time, as explained above, and on the reduction in the pressure ofthe fluid in the chamber 22 at the opposite face of the piston 26, thepiston 26 will be moved upwardly into engagement with a gasket 4|, bythe fluid under pressure in the chamber 26 so as to unseat the valve32.and release fluid from the operating chamber '26 through the pipe 34to the atmosphere.

Since with the float, 46 cutting off the flow of fluid under pressure tothe chamber 26, the only fluid in this chamber is that which is suppliedby leakage past the piston 26, and as this chamber is of relativelysmall volume, when the piston 26 is moved upwardly to unseat the valve32, the pressure of the fluid in the chamber 26 will be quickly reducedbelow that of the fluid in the chamber 22 so that the piston 26 will bemoved downwardly to seat the valve 32 and cut off the release of fluidfrom the chamber 26.

When the release of fluid under pressure from the reservoir I throughtheservicepipe 8 is cut ofi, fluid from the reservoir I continues to flowthrough the passage in the tubular sleeve I6 and past the valve disc I6,which is loosely, mounted on the tube I2, to. thecontrol chamber 6 andtherefrom through the passage 24 to the chamber 22 at the face of thepiston 20 to increase the pressure of the fluid in these chamberssubstantially, to the pressure of the fluid in the reservoir I.

On this increase in the pressure of the fluid in the chamber 2 2, fluidleaks therefrom past the piston 26 and the packing ring 30 to thechamber 26 to increase the pressure of the fluid in the chamber 26 tothe pressure of the fluid inthe reservoir I.

Water condensing out of the fluid supplied to the reservoir will flow bygravityto the cup 36 which is mounted at the lowest portion of thereservoir I, and on a predetermined increase in the level of the liquidin the cup 36, the float 46 will be lifted away from the face of themember 42 so as to open communication from the reservoir I to thepassages 44 leading to'the tube I2, so that liquid may flow from the cup36 to the passages 44 leading to the -tube I2. Liquid will notflow'upwardly in the passage in the tube I2 at this time, however, asits flow is prevented by the fluid under pressure trapped in the tube I2and in the chamber 26. 7

On a subsequent withdrawal of fluid from the reservoir I through theservice pipe 8, there is a reduction in the pressure of the fluid in'thecontrol chamber 6, and a similar reduction in the pressure of the fluidin the chamber 22 at the upper face of the piston '20. On this reductionin the pressure of the fluid-in the control chamber 6, fluid underpressure from the reservoir I flows thereto through the passage in thetubular sleeve I and past the valve disc I6, which is forced upwardlyagainst the spring I8. The valve disc I6, however, offers'resistance tothe flow of fluid from the reservoir I to the control chamber 6 so thata small diiference is maintained between the pressure of the fluid inthe chamber 6, and in the reservoir I as long as fluid is released.through the service pipe 8 at a substantial rate.

On a reduction in the pressure of the fluid in the chamber 22 at theface of the piston 26 to a predetermined value below the pressure of thefluid in the operating chamber 26 at the opposite face of the piston 26,which chamber is at substantially the pressure of the fluid in thereservoir I at this time, the piston 26 is moved upwardly intoengagement with the gasket II by the fluid under pressure in theoperating chamber 26, which exerts enough force on the piston toovercome the opposing force of the fluid under pressure in the chamber22 and to also overcome the resistance to movement of the piston 20offered by the packing ring 30.

On upward movement of the piston 26, the valve 32 carried thereby ismoved away from its seat so as to open communication between theoperating chamber 26 and the pipe 34.

On movement of the valve 32 away from its seat, fluid in the chamber 26may flow therefrom at a restricted rate through the choke t6 and throughthe pipe 34 to the atmosphere. On the release of fluid from theoperating chamber 26, the higher pressure of the fluid in the reservoirI forces liquid from the cup 36 through the passages 44 and the tube I2to the chamber 26, and past the open valve 32 and through the choke 46to the pipe 34 through which it is drained to the atmosphere.

The choke 40 restricts the flow of liquid from the chamber 26 throughthe pipe 34 to a rate substantially less rapid than liquid underpressure is supplied to the chamber 26 from the reservoir I as long asthe float 46 is held out of engagement with the upper face of the member42. As a result, the pressure of the liquid in the operating chamber 26will be maintained substantially at the pressure of the fluid in thereservoir I, and the piston 26 will be held in engagement with thegasket 4 I.

When the withdrawal of fluid under pressure from the reservoir I throughthe service pipe 8 is cut off, the pressure of the fluid in the controlchamber 6 will build up substantially to the pressure of the fluid inthe reservoir I by the flow of fluid to the control chamber 6 past thevalve disc I6, which loosely fits the tube I2. On this increase in thepressure of the fluid in the chamber 6, there will be a similar increasein the pressure of the fluid in the chamber 22 at the face of the piston20.

If the withdrawal of fluidfrom the reservoir I through the service pipe8 is cut off before the level of the liquid in the cup 36 is reduced soas to permit the float 46 to be moved into engagement with the face ofthe member 42, liquid will continue to flow from the reservoir I to thepassage in the tube I2, and to the operating chamber 26, so that thepiston 20 is held in engagement with the gasket M by the piston packingring 36, which engages the wall of the bore in which the piston ismounted, and which develops considerable frictional resistance tomovement, and by the liquid under pressure in the operating chamber 26at the opposite face of the piston,

which, as pointed out above, is substantially at the pressure of thefluid in the reservoir because of the choke 40.

As the piston 26 is held in its upper position, liquid will continue toflow from the reservoir I to the tube I2, and thence through thepassages 28 to the operating chamber 26, from which it flows past theopen valve 32 and through the choke 40 in the tube 34 leading to theatmosphere.

After a time interval the level of the liquid in the cup 36 will havebeen lowered by the flow of liquid therefrom to the tube I2, and thenceto the atmosphere, sufficiently topermit the float 46 to move intoengagement with the upper face of the member 42 to cut off the flow ofliquid from the reservoir I through the passages 44 leading to the tubeI2, thereby cutting off the supply of fluid to the operating chamber 26.

When the flow of liquid from the reservoir I to the operating chamber 26is out 01f by movement of the float 44 into engagement with the upperface of the member 42, liquid continues to flow from the operatingchamber past the open valve 32, and through the choke 46 in the tube 34leading to the atmosphere, until the pressure of the fluid in theoperating chamber 26 has been reduced to a predetermined value below thepressure of the fluid in the chamber 22, which is at substantially thepressure of the fluid in the reservoir I.

When the pressure of the fluid in the operating chamber 26 has beenreduced to a predetermined value below the pressure of the fluid in thechamber 22, the piston 26 is moved downwardly by the fluid underpressure in the chamber 22 against the opposing force of the fluid inthe chamber 26 and of the resistance to movement of piston packing ring36 so as to move the valve 32 to the seated position to cut off thefurther release of liquid from the chamber 26 to the atmosphere. 7

After downward movement of the piston 22 to move the valve 32 to theseated position, fluid under pressure will leak from the chamber 22 tothe operating chamber 26 to increase the pressure of the fluid in thischamber substantially tothe pressure of the fluid in the reservoir I.-As a result any liquid remaining in the tube I2 will gradually flow fromthis tube by gravity to the cup 36, and will not remain in the tube I2where it might cause injury to portions of the valve device if it shouldfreeze.

From the foregoing it will be seen that when the valve device isoperated to drain, liquid from the reservoir, it continues to releaseliquid until the level of the liquid in the reservoir is reduced to apredetermined point, even though the withdrawal of fluid from thereservoir I through the service pipe 8 is cut off before the level ofthe liquid has been reduced to this extent.'

This valve device also operates to cut off the release of fluid underpressure from the reservoir I through the valve device after the levelof the liquid has been reduced to a predetermined point, even though thewithdrawal of fluid under pressure to the service pipe 8 continues.

Thus if, while the piston 26 is in its upper position in engagement withthe gasket M, the withdrawal of fluid under pressure through the servicepipe 6 continues after liquid has been expelled from the cup 36 to lowerthe level of this liquid so as to permit the float 46 to be moved intoengagement with the upper face of member 42, the float will cut off thefurther flow of fluid iii) from the reservoir I to the passages 44 inthe member 42, and thence to the tube I2 leading to the operatingchamber 26.

When the flow of fluid from the reservoir I to the operating chamber 26is out off, fluid under pressure continues to be released from theoperating chamber 26 past the open Valve 32, and through the choke 40 inthe pipe 34 leading to the atmosphere, until the pressure of the fluidin the chamber 26 has been reduced to a value somewhat less than thepressure of the fluid in the chamber 22 at the opposite face of thepiston 29.

Vfhen the pressure of the fluid in the chamber 26 has been reduced to apredetermined value below the pressure of the fluid in the chamber 22,the piston 29 is moved downwardly by the fluid under pressure in thechamber 22 against the opposing force of. the fluid under pressure inthe chamber 23 and of the resistance to movement of the piston packingring 30, and the valve 32 carried by the piston is moved to the seatedposition to cut off the release of fluid from the operating chamber 26through the pipe 34.

On movement of the piston 26 to the seated position, fluid underpressure from the chamber 22 will leak past the piston 20 and thepacking ring iii) to the operating chamber 26 to gradually increase thepressure of the fluid in the operat-- ing chamber to cause the liquid inthe tube I2 to flow therefrom by gravity through the cup 556,as'explained in detail above.

When the withdrawal of fluid from the reservoir I through the servicepipe 8 is out ofl, the pressure of the fluid inthe control chamber 6 andin the chamber 22' is increased to thepressure of the fluid in thereservoir I by flow of fiuid from the reservoir to the control chamber 6past the valve disc I6. On this increase in the pressure of the fluid inthe chamber 22 fluid leaks therefrom past the piston 20 and the packingring 30 to the chamber to increase the pressure of the fluid in thischamber substantially to the pressure of the fluid in the reservoir I.

On subsequent withdrawals of fluid under pressure from the reservoir Ithrough the service pipe 8, this automatic drain valve device operatesas described in detail above to drain liquid from the reservoir untilthe liquid therein has been reduced to a predetermined level.

While one embodiment of the improved automatic drain valve deviceprovided by this invention has been illustrated and described in detail,it should be understood that the invention is not limited to thesedetails of construction, and that numerous changes and modifications maybe made without departing from the scope of. the following claims.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. An automatic drain valve device for a reser-- voir comprising a bodyhaving a chamber therein, valve means operated on a predeterminedreduction in the pressure of the fluid in said chamber below thepressure of the fluid in the reservoir for supplying fluid'from thereservoir to said chamber, a release passage communicating with saidchamber through which fluid is withdrawn from said chamber andconsequently from said reservoir past said valve means, a movableelement subject to the opposing pressures of the fluid in said chamberand of the fluid in a chamber adapted to be charged with fluid atreservoir pressure, a valve operated by said element for controlling apassage through which water accumulating in said reservoir may bedrained, and means responsive to the level of the liquid in saidreservoir for controlling the flow of fluid from said reservoir to saidpassage.

2. An automatic drain valve device for a reservoir comprising a bodyhaving a chamber therein, valve means operated on a predeterminedreduction in the pressure of the fluidin said chamber below the pressureof the fluid in the reservoir for supplying fluid from the reservoir tosaid chamber, a release passage communicating with said chamber throughwhich fluid is withdrawn from said chamber and consequently from saidreservoirpast said valve means, a movable element subject to theopposing pressures of. the fluid in said chamber and of the fluid in achamber adapted to be charged with fluid at reservoir pressure, a valveoperated by said element for controlling a passage through which wateraccumulating in said reservoir may be drained, and means operated on apredetermined reduction in the level of the liquid in said reservoir tocut off the flow of fluid from said reservoir to said passage.

3. An automatic drain valve device for a reservoir comprising a bodyhaving a chamber therein, valve means operated on a predeterminedreduction in the pressure of the fluid in said chamber below thepressure of the fluid in the reservoir for supplying fluid from thereservoir to said chamber, a release passage communicating with saidchamber through which fluid is withdrawn from said chamber andconsequently from said reservoir past said valve means, a movableelement subject to the opposing pressures of the fluid in said chamberand of the fluid in a chamber adapted to be charged with fluid atreservoir pressure, a valve operated by said element for releasing fluidfrom the lower portion of the reservoir, and means responsive to thelevel of the liquid in said reservoir for controlling the flow of. fluidfrom said reservoirto said valve.

4. An automatic drain valve device for a reser-- voir comprising a bodyhaving a chamber therein, valve means subject to the opposing pressuresoi the fluid in said chamber and of the fluid in the reservoir andcontrolling the flow of fluid from the reservoir to the chamber, meansyieldingly opposing movement ofrsaid valve means to a position to permitfluid to flow from the reservoir to said chamber, a release passagecommunicating with said chamber through which fluid is withdrawn fromsaid chamber and consequently 'lower portions of the said reservoir,said body having a control chamber having a release passagecommunicating therewith through which fluid may be withdrawn from saidchamber, valve means subject to the opposing pressures of the fluid inthe reservoir and said control chamber for controlling the flow of fluidfrom the reservoir to said chamber, yielding means opposing movement ofsaid valve means to permit fluid to flow from the reservoir to saidcontrol chamber, the

body having an operating chamber therein. a movable element subject tothe opposing pressures of the fluid in said operating chamber and of thefluid in said control chamber for releasin fluid irom said operatingchamber, and means responsive to the level of the liquid in thereservoir for supplying fluid from the lower portion of the reservoir tosaid operating chamber.

, 6. In combination, a reservoir adapted to contain fluid underpressure, a body associated with saidreservoir and disposed verticallyabove the lower portions of the said reservoir, said body having acontrol chamber having a release passage communicating therewith throughwhich fluid may be withdrawn from said chamber, valve means subject tothe opposing pressures of the fluid in the reservoir and said controlchamber for controlling the flow of fluid from the reservoir to saidchamber, yielding means opposing movement of said valve means to permitfluid to flow from the reservoir to said control chamber, said bodyhaving an operating chamber therein, a movable element subject to theopposing pressures of the fluid in said operating chamber and of thefluid in said control chamber for releasing fluid from said operatingchamber, means responsive to the level of the liquid in the reservoirfor supplying fluid from the lower portion of the reservoir to saidoperating chamber, and means for retarding movement of said movableelement.

7. An automatic drain valve device for a reservoir comprising a bodyhaving a control chamber therein having a release passage communicatingtherewith through which fluid may be withdrawn from said chamber, valvemeans subject to the opposing pressures of the control chamber and ofthe reservoir for controlling the supply of fluid from the reservoir tothe control chamber, said body having a bore therein, a pistonreciprocable in said bore and being subject to the opposing pressures ofthe fluid in the control chamber and of the fluid in an operatingchamber communiacting with the lower portion of the reservoir, thepiston controlling the release of fluid from said operating chamber andcarrying a packing ring having frictional engagement with the walls ofthe bore in which the piston is mounted to retard movement of the pistonin said bore.

8. An automatic drain valve device for a reservoir, a body having acontrol chamber therein having a release passage communicating therewiththrough which fluid may be withdrawn from said chamber, valve meanssubject to the opposing pressures of the control chamber and of thereservoir for controlling the supply of fluid from the reservoir to thecontrol chamber, said body having a bore therein, a piston reciprocablein said bore and being subject to the opposing pressures of the fluid inthe control chamber and of the fluid in an operating chamber, the pistoncontrolling the release of fluid from said operating chamber, andcarrying a packing ring having frictional engagement with the walls ofthe bore in which the piston is mounted to retard movement of the pistonin said bore, and means responsive to the level of the liquid in saidreservoir for controlling the supply of fluid from the reservoir to theoperating chamber.

9. An automatic drain valve device for a reservoir, a body having acontrol chamber therein having a release passage communicating therewiththrough which fluid may be withdrawn from said chamber, valve meanssubject to the opposing pressures of the control chamber and of thereservoir for controlling the supply of fluid from the reservoir to thecontrol chamber, said body having a bore therein, a piston reciprocablein said bore and being subject to the opposing pressures of the fluid inthe control chamber and of the fluid in an operating chamber, the pistoncontrolling the release of fluid from said operating chamber, andcarrying a packing ring having frictional engagement with the walls ofthe bore in which the piston is mounted to retard movement .of thepiston in said bore, and means responsive to the level of the liquid insaid reservoir for controlling the supply of liquid from. the lowermostportion of the reservoir to said operating chamber.

10. In an automatic drain valve device for a reservoir, a body having acontrol chamber therein having a release passage communicating therewithfor withdrawing fluid from the reservoir, valve means subject to theopposing pressures of the fluid in said control chamber and in thereservoir and controlling the flow of fluid from the reservoir to thecontrol chamber, said body having an operating chamber therein, amovable element subject to the opposing pressures of the fluid in thecontrol chamber and of the fluid in the operating chamber for releasingfluid from said operating chamber at one rate, and means for supplyingfluid from the lower portion of the reservoir to said operating chamberat a rate more rapid than said one rate.

11. In an automatic drain valve device for a reservoir, a body having acontrol chamber therein having a release passage communicating therewithfor withdrawing fluid from the reservoir, valve means subject to theopposing pressures of the fluid in said control chamber and in thereservoir and controlling the flow of fluid from the reservoir to thecontrol chamber, said body having an operating chamber therein, amovable element subject to the opposing pressures of the fluid in thecontrol chamber and of the fluid in the operating chamber for releasingfluid from said operating chamber at one rate, and means responsive tothe level of the liquid in said reservoir for supplying fluid from thelower portion of the reservoir to said operating chamber at a rate morerapid than said one rate.

12. An automatic drain valve device for a reservoir having a drainpassage communicating with the reservoir at or adjacent the bottomthereof and a discharge passage through which fluid under pressure isdischarged from the reservoir, the drain valve device comprising meansinterposed in the communication through which fluid flows from thereservoir to said discharge passage for reducing the pressure of thefluid in the discharge passage relative to the pressure of the fluid inthe reservoir on the withdrawal of fluid under pressure from thereservoir through the discharge passage, a movable element having acontrol chamber at one side open to said discharge passage and anoperating chamber at the opposite side open to the drain passage, valvemeans controlling communication from said operating chamber to anatmosphere outlet and operated by said element upon a reduction in fluidpressure in said control chamber for opening communication from saidoperating chamber and said drain passage to the atmosphere to permitdrainage of water from said reservoir, and means operated on apredetermined reduction in the level of the liquid in the reservoir toout 01f communication between the reservoir and said drain passage.

13. An automatic drain valve device for a reservoir having a dischargepassage through which fluid is discharged from the reservoir, the drainvalve device comprising means interposed in the communication throughwhich fluid flows from the reservoir to the discharge passage for reduc-7 ing the pressure of the'fluid in the discharge passage relative to thepressure of the fluid in the reservoir on the withdrawal of fluid underpressure from the reservoir through the discharge passage, a movableelement having a control chamber at one side open to said dischargepassage and an operating chamber at the opposite side, means responsiveto the level of the liquid

